A general trend in wind power technology is increasing sizes of wind turbines. As a result of this, and the increased number of turbines manufactured, there is a desire to make manufacturing processes more effective and faster. In particular wind turbine blades, normally made of composite materials such as glass reinforced plastics, with lengths sometimes above 50 meters, could benefit from more efficient manufacturing methods.
Automatic fiber placement machines are known in the field of composite materials as making the manufacturing more efficient. They involve moving a fiber placement head past a mould and depositing fiber tows on the mould, see e.g. U.S. Pat. No. 6,692,681 B1, US2007044896A1 or WO2005105641A2. Although such machines improve manufacturing efficiency compared to manual fiber placement methods, there is still room for improvements where more than one fiber material is used for the product produced in the mould.